Title says it all.
Whether or not you believe Whitehurst is a true backup solution, the reality suggests that he'll be around through next season. The team has too many other priorities in the offseason to be adding "backup QB" to the list.

If PR goes down for a long period, we can basically write off the season - hoping that the backup can take us to the promised land is lofty.

Risking injury to the team's foundation for the forseeable future in two meaningless games seems foolish.

Maybe, in his last 2 games as a Chargers HC, norv will make two of the best decisions of his entire tenure. I am quite sure that he knows what happened to the QB that came before Rivers.